Feedback avoidance - acoustic amp vs feedback buster

Jim_Cross · #1 09-01-2018, 12:46 AM

I've just had a James May Ultratonic installed in my guitar and have a couple of gigs coming up. I play in an acoustic trio - 2x guitars, keys, 2x vocals. While our stage volume isn't that loud, I have had problems with feedback playing in this band before, and I hate fighting with feedback on stage.
The guitar tech who inalled the pickup recommended using an acoustic amp as a monitor, avoiding my guitar going through foldback monitors. However, given that the other guitar will be through the monitors will that really help? Am I better off sucking it up and using a feedback buster?

jonfields45 · #2 09-01-2018, 06:44 AM

Anything on the floor that hits the guitar before your ears is going to be a problem with a SBT. I would go with the sound hole cover in your situation. I convinced by duo partner to give up on floor monitors long ago and that solved our K&K problems.

RobKay · #3 09-01-2018, 07:25 AM

If they are soundboard transducers i think you will run into problems when playing with a band whatever the setup, it turns the front of the
guitar into a massive microphone......others will probably have differing opinions but this is what i find from my experience.....

ljguitar · #4 09-01-2018, 11:27 AM

Quote:

Originally Posted by Jim_Cross

I've just had a James May Ultratonic installed in my guitar and have a couple of gigs coming up. I play in an acoustic trio - 2x guitars, keys, 2x vocals. While our stage volume isn't that loud, I have had problems with feedback playing in this band before, and I hate fighting with feedback on stage.
The guitar tech who inalled the pickup recommended using an acoustic amp as a monitor, avoiding my guitar going through foldback monitors. However, given that the other guitar will be through the monitors will that really help? Am I better off sucking it up and using a feedback buster?

Hi Jim
For me it's not an either/or solution.

I never put all my eggs in a single basket when it comes to keeping a strong presence of my acoustic in the mix.

I've tried mixed solutions…either acoustic amp as monitor and take my guitar out of my monitor, or feedback buster (soundhole plug). And there are times I've just worked without a monitor directly in front of me. I'm old school (and nearly 70 yrs old) so I worked without monitors for 30 years back-in-the-day. And there are times I place my acoustic amp about 3-5 feet behind me on a waist-high stand and angle it so it's aimed toward the back of the head and have them take my guitar out of the monitor (my favorite option). Either is adequate for me, and very workable.

Did I mention…I never put all my eggs in a single basket when it comes to keeping a strong presence of my acoustic in the mix.

Then there are venues where they are running multiple sub-woofers in the house and they are triggering things on stage, so I just grab the big-black-plug (or a Lute Hole Cover) and go. This is the ultimate solution for controlling feedback. Since I use a K&K dual source and the mic resides close to the soundhole aimed out of the soundhole I have to reverse phase on the mic, but all my preamps have that capability, and I'm good to go. And…I never put all my eggs in a single basket when it comes to keeping a strong presence of my acoustic in the mix.

Both processes work equally well, and I vary them by the venue. A feedback buster is in the pick drawer of each guitar, and I'm not afraid to use it.

Since I'm going through the house system via my pickup/internal microphone I'm not concerned about me hearing my acoustic sound on stage at all.

Worst case scenario - I use the big-black-plug AND work without a monitor or stage amp. But that's not THAT difficult. When one is playing on a very noisy/volume-turned-up-drummer-too-loud-bass/electric amps-loaded-stage…thankful for my big-black-plug.

I AM concerned about a strong presence of my guitar in the mix.

Hope this adds to the discussion…

Beagle1 · #5 09-01-2018, 02:00 PM

Quote:

Originally Posted by Jim_Cross

I've just had a James May Ultratonic installed in my guitar and have a couple of gigs coming up. I play in an acoustic trio - 2x guitars, keys, 2x vocals. While our stage volume isn't that loud, I have had problems with feedback playing in this band before, and I hate fighting with feedback on stage.
The guitar tech who inalled the pickup recommended using an acoustic amp as a monitor, avoiding my guitar going through foldback monitors. However, given that the other guitar will be through the monitors will that really help? Am I better off sucking it up and using a feedback buster?

Hi Jim_Cross,

I was just wondering if you actually have gigged with the Ultratonic yet? It is supposed to offer the feedback immunity of an undersaddle pickup if installed and configured correctly. So, maybe you would be fine without doing anything different than you have in the past, or at most maybe just add a sound hole plug as that is easy and inexpensive. At any rate, I would be curious as to what your experience is in gigging with the Ultratonic. I am thinking about getting Ultratonics installed in a couple of my Martins. Let us know how it goes!

Jim_Cross · #6 09-01-2018, 02:47 PM

Thanks all, interesting discussion!

ljguitar - great advice, thank you! I will keep a soundhole plug with me, I'd just like to give myself the best chance of not having to use it.

Beagle1 - I have gigged with it once, but there were no monitors, so I can't make a judgement on the feedback resistance yet.
The guitar tech and I did test it against a K&K-equipped guitar in the workshop, and I preferred the tone of the Ultratonic (more clarity and a more balanced tone with less lows and more highs). We also found it was significantly more feedback resistant. However, I think the feedback resistance is a result of the circuit effectively notching out the guitar's fundamental frequency, which will be effective when there's only 1 guitar, but if there's another guitar putting out that frequency strongly I suspect it's still going to be prone to feedback.

James May · #7 09-01-2018, 03:35 PM

Quote:

Originally Posted by Jim_Cross

...We also found it was significantly more feedback resistant. However, I think the feedback resistance is a result of the circuit effectively notching out the guitar's fundamental frequency, which will be effective when there's only 1 guitar, but if there's another guitar putting out that frequency strongly I suspect it's still going to be prone to feedback.

I think there is a slight misconception on how the Ultra Tonic achieves its feedback immunity.

It is actually not a notch of the fundamental resonance. I can certainly see how one might come to that conclusion from the installation instructions, because in a way that’s what APPEARS to be happening. But in reality, the switch selection setup procedure is merely finding the optimum amount signal level from the feedback suppression disc to mix in with the main string sensor discs. Once that optimum balance is achieved, and because the suppression disc is out of phase, most of the chamber and top plate resonance modes will cancel out, thereby making the guitar very immune to feedback, and cleaning out all the low end mud and boom that plagues a K&K. (The main chamber resonance typically goes down by at least 10dB and that is a lot!)

This immunity extends not only to the guitar’s own excitation caused by strings, but also from other audio coming through monitors and hitting the top of the guitar.

I hope that clarifies things a bit. I don’t expect you’ll have much feedback problem in a louder environment with floor monitors and sound from other instruments, but there is always a limit. Under very loud conditions you may need to resort to a notch filter.